Many systems have been proposed which are designed so as to attempt to capture the heat that passes through the flue, and recirculate it or reuse it within the furnace in order to improve upon the efficiency of the furnace. In most cases, these systems use a pipe which surrounds and is concentric with the flue. A blower is usually connected to the upper part of the pipe so as to force the air downwardly between the pipe and the flue, thus picking up heat from the flue as the gases in the flue pass upwardly. In the usual system, this heated air is passed back into the plenum chamber and used as preheated air in the furnace. One such standard type system is shown in U.S. Pat. No. 2,361,643 issued Oct. 31, 1944.
Humidification is also quite commonly used during the winter time. Such humidification is usually achieved either by the use of a spray or a membrane within the area immediately adjacent to the plenum chamber which provides the main hot air outlet from the furnace. Such humidification does not take advantage of any particular heat transfer, and, therefore, supplies only humidity to the air without improving the heat exchanger characteristic and, thus, the efficiency of the furnace. efficiency of the furnace.
Accordingly, it is an object of the present invention to provide a system which utilizes sensible and latent heat of the furnace flue gas to provide increased efficiency in the heating of the home and, additionally, provides the desired humidification.
A further object of the present invention is to provide an economizer system which provides increased efficiency and humidification and which may be easily adapted to existing furnaces.
These and other objects of the invention will become apparent from the following descriptions taken together from the accompanying drawings.